In my organic chemistry lab, we recently had an experiment where we were given a mixture of 50:50 ethanol & ethylene glycol. We were supposed to perform a simple distillation to calculate the percent recovery. Based on my readings, I found that the ethanol has a lower boiling point than ethylene glycol and concluded that ethanol would be the compound that would vaporize and transfer over to the cooled flask where it could condense back. At the end of the lab, we just weighed the distillate and the holdup.
My question was, how do you know if the simple distillation process was successful? I assumed that it was successful based on the fact that it produced a distillate, but I realized that can't be the only reason. The difference in boiling point was large enough to be performed as a simple distillation, but how can I conclude that it was overall successful?
Also, based on this, can I figure out if there is an azeotrope for the boiling points of the two compounds? I read that azeotropes "prefer" to be boiled into the gas phase together, but doesn't that imply that both compounds could have condensed, making the simple distillation process unsuccessful?